Laser projectors are used in a variety of manufacturing operations. For example, laser projectors may be used for part placement in structural assemblies. In this regard, one or more laser projectors may be installed in a work zone and may emit a laser beam for projecting geometric patterns directly onto the surface of a structural assembly being assembled in an assembly jig. The geometric patterns projected by the laser beam may facilitate a relatively precise location of a component relative to other components of the structural assembly or relative to a frame of reference without the use of hard tooling.
The laser beam may be projected as a relatively narrow beam (e.g., 0.030 inch). The laser beam is preferably projected onto the surface of the structural assembly at a nominal positional accuracy. The positional accuracy with which the laser beam is projected is preferably less than the manufacturing tolerances of the structural assembly. For example, the laser projector may have a nominal positional accuracy of +/−0.015 inch at a nominal distance of 15 feet to enable locating a component having a nominal locational tolerance on the structural assembly of +/−0.030 inch.
Prior to operating a laser projector after a period of nonuse or at periodic intervals, it is necessary to verify that the positional accuracy of the laser projector is within the nominal tolerances. In this regard, the positional accuracy with which the laser beam is projected may be adversely affected by degradation or failure of internal components such as galvanometers of the laser projector. Conventional methods for verifying the positional accuracy of a laser projector include the use of a calibration pattern mounted to a structure. The laser beam is projected against the calibration pattern and measurements are recorded of the deviation of the laser beam relative to the calibration pattern.
It is generally desirable to calibrate the positional accuracy of the laser projector at various locations within a work zone containing the assembly jig. For example, it is generally desirable to calibrate the positional accuracy of a laser projector at opposite sides and at upper and lower sides of the assembly jig. It is also generally desirable to account for changes in the location and/or the size of the calibration pattern within the work zone due to changes in temperature which may cause the calibration pattern to expand or contract. In addition, once the laser projector is calibrated, it may be desirable to remove the calibration pattern from the work zone to avoid interference of the calibration pattern with manufacturing operations.
As can be seen, there exists a need in the art for a system and method for calibrating a laser projector in a manner that accounts for changes in the size and the relative location of the calibration pattern within the work zone due to changes in temperature of the manufacturing environment. In addition, there exists a need in the art for a system and method for calibrating a laser projector wherein the calibration pattern may be located at various positions within the work zone and/or such that the calibration may be entirely removed from the work zone to avoid interfering with manufacturing operations.